Some movies you just have to see. I make sure I see them. Why? Because movies are visual experiences and little else as far as I'm concerned.
A story that I can't quite see through is a plus, but not necessary. Sometimes moviemakers are trying to be too damned clever. Take 'Seven Psychopaths' for example. Very damned clever - and almost too clever for its own good. Why not? Because Seven Psychopaths had decent moments of drama, and decent moments of manufactured drama is what makes anything interesting, especially baseball when you have a bad seat.
Poor acting and bad dialog will not ruin a movie with a reasonably twisty plot and great visuals. Tom Cruise is generally bad enough so that he tilts an otherwise good movie into the gutter. But even he couldn't kill Oblivion, which is excellently visual, plenty twisty and nicely dramatic.
Don't get me wrong - this movie was made for a younger Harrison Ford and Tom gets Cruise-stink all over it. But this time he tries so hard to be that good-old Earth boy with his football monologue, beat-up aviator glasses, moldy books and vinyl record collection that you kinda feel sorry for him and his generation. By being a person with barely enough of a soul to remember what he used to be, the filmmakers cast Cruise perfectly. Here's a hero with no audience and a memory wipe. Nice.
With that oblique spoiler, you should still see it if you haven't. It's one for the big screen, and also Morgan Freeman is more voiceover when he explains the whole thing. I have to say, in terms of believability, Oblivion has it all over Prometheus.